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Structure and kinematics of a protostar: mm-interferometry of L 1157

F.Gueth tex2html_wrap_inline1451 , S.Guilloteau tex2html_wrap_inline1451 , A.Dutrey tex2html_wrap_inline1451 , R.Bachiller tex2html_wrap_inline1453
tex2html_wrap_inline1451 IRAM, 300 rue de la piscine, F-38406 St Martin d'Hères, France
tex2html_wrap_inline1453 OAN, Apartado 1143, E-28800 Alcalá de Henares, Spain
Abstract: We present high angular resolution (2.5'') interferometric images of tex2html_wrap_inline1343  ( tex2html_wrap_inline1583 ), tex2html_wrap_inline1585  ( tex2html_wrap_inline1583 ), and tex2html_wrap_inline1589  2.7 mm continuum emission around L1157-mm, a suspected protostar powering an energetic molecular outflow. The continuum emission consists in two distinct components. The Class 0 object L1157-mm is seen as a compact source of size tex2html_wrap_inline1591 (440 AU) and mass tex2html_wrap_inline1593 , which is marginally resolved and elongated perpendicular to the outflow axis. In addition, spatially-extended low-level emission is observed and likely arises at the heated edges of the cavity excavated by the outflow in the surrounding envelope. Simple modelisation shows that such an interacting structure can explain the observed morphology and the spectral energy distribution of the source.

The line observations indicate that tex2html_wrap_inline1343   mostly originates from the envelope and the limb-brightened edges of the outflow, whereas the tex2html_wrap_inline1585 emission is more directly associated with the compact continuum source. Weak evidence for rotation has been found. Comparison of the two line tracers shows proeminent redshifted self-absorption in the tex2html_wrap_inline1343   spectrum which is very suggestive of infall motions. The infalling medium seems to be confined in a large (a few thousands AU) flattened structure.

These observations provide a quite detailed description of the structure of a Class 0 protostar, which appears to have a complex vicinity where the outflowing and accreting phenomena are closely linked together (Fig. 4)

 

  figure812


Figure: 2.5'' observations of the protostar L 1157-mm: (Left) tex2html_wrap_inline1585 J=1-0 (thick histogram), tex2html_wrap_inline1343 J=1-0 (filled) and tex2html_wrap_inline1343 J=1-0 interferometric + single-dish (thin) spectra observed towards the central position. (Right) tex2html_wrap_inline1287  mm continuum emission (greyscale) surimposed with the integrated CO emission: the extended component of the continuum emission is associated with the edges of the molecular outflow. The white ellipse is the formal result of a fit of the compact central source.


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Next: The interstellar medium in Up: Scientific results Previous: The Gravitational Lensing Nature

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